Terms of the Trade: What Does "Plumb" Mean? Terms of the Trade: What Does "Plumb" Mean?
If you don't what know the term "plumb" means, you may be surprised to hear that it doesn't directly have anything to do with plumbing. It's actually used to describe when a edge or surface is perpendicular to to a level line, with true vertical orientation. (Think when you're framing a house or installing a door jamb.) To know if a surface is plumb, you can use a level, which usually has at least one vial to read plumb, or a plumb bob, which is a weight suspended by a string.